package Practice;

public class OnlyOne {
    public static void main(String[] args) {
        int[] arr=new int[]{1,1,3,3,7,7,8,99,99,11,11};
        int x=0;
        for(int i=0;i<arr.length;i++){
            x^=arr[i];
        }
        System.out.println(x);
    }
}
